Non-invasive quantitative multilayer assessment method and resulting multilayer component

ABSTRACT

A method of analyzing layer thickness of a multilayer component is provided. The method includes: creating an opening having a predefined geometry partially into the multilayer component at a selected location on a surface of the multilayer component. The multilayer component includes a plurality of material layers including a substrate and a bond coat. The opening exposes each of the plurality of material layers including the substrate. Contrast of the exposed plurality of material layers can be increased. An image is created of the exposed layers in the opening using a digital microscope, and thickness of a bond coat, thickness of a depletion layer\ and/or thickness of an oxide layer is calculated from the image and based on the predefined geometry of the opening. Repairing the opening, allows the multilayer component to be used for an intended purpose after testing, e.g., re-installed and reused in a gas turbine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of European Patent Application No.18210779.7 filed Dec. 6, 2018, the disclosure of which is hereinincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The disclosure relates generally to non-destructive material testing,and more particularly, to a method of analyzing quantitative data aboutlayer(s) of a multilayer component, and a resulting multilayercomponent.

Quantitative investigations and quality checks of materials propertiesare oftentimes required to determine, for example, an applied coatingthickness, a depletion level, etc. Such assessments are oftentimesrequired for process qualification, regular production monitoring,determining the remaining lifetime for a multilayer component or as aninitial assessment to determine the scope of a repair for a multilayercomponent. In order to conduct these assessments, a cut up is taken froma commercial component. Consequently, the component is destroyed(scrapped) and needs to be replaced by a new part. Limitednon-destructive tests are available to assess, e.g., interfacedelamination or layer thicknesses with thermography, etc. for ceramiclayers on metallic substrates. However, these approaches lack theability to provide quantitative data regarding lifetime relevantproperties, and in particular, depletion of a bond coat. In addition,such assessments cannot be performed on-site (neither in-situ nor on adismounted part).

BRIEF DESCRIPTION OF THE INVENTION

A first aspect of the disclosure provides a method of analyzing layerthickness of a multilayer component, the method comprising: creating anopening having a predefined geometry partially into the multilayercomponent at a selected location on a surface of the multilayercomponent, wherein the multilayer component includes a plurality ofmaterial layers including a substrate and a bond coat and the openingexposes each of the plurality of material layers including thesubstrate; creating an image of the exposed plurality of material layersin the opening using a digital microscope; and calculating at least athickness of the bond coat of the exposed plurality of material layersfrom the image and based on the predefined geometry of the opening.

A second aspect of the disclosure provides a multilayer component,comprising: a substrate; a bond coat over the substrate; a thermalbarrier coating (TBC) layer over the bond coat, the TBC layer having afirst outer surface having indication of exposure to a hot gas pathenvironment; and a filled opening in the substrate, the bond coat andthe TBC layer, the filled opening including: a substrate repair fillfilling the filled opening in the substrate; a bond coat repair fillfilling the filled opening in the bond coat, and a thermal barriercoating (TBC) plug filling the filled opening in the TBC layer, the TBCplug having a second outer surface having no or less indication ofexposure to the hot gas path environment.

A third aspect of the disclosure includes a method of analyzing layerthickness of a multilayer component, the method comprising: drilling tocreate an opening having a predefined geometry partially into themultilayer component at a selected location on a surface of themultilayer component, wherein the multilayer component includes aplurality of material layers including a substrate, a bond coat over thesubstrate, and wherein the opening exposes each of the plurality ofmaterial layers; increasing a contrast of the exposed plurality ofmaterial layers exclusively in the opening from that present after theopening creating by polishing the exposed plurality of material layers,and etching the exposed plurality of material layers; creating an imageof the exposed plurality of material layers in the opening using adigital microscope; calculating at least a thickness of the bond coatfrom the image and based on the predefined geometry of the opening; andrepairing the opening, allowing the multilayer component to be used foran intended purpose thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the disclosure taken in conjunction with the accompanyingdrawings that depict various embodiments of the disclosure, in which:

FIG. 1 shows a perspective view of an illustrative multilayer componentin the form of a turbine blade.

FIG. 2 shows a cross-sectional view of illustrative layers of amultilayer component.

FIG. 3 shows a cross-sectional view of creating an opening according toone embodiment of the disclosure.

FIG. 4 shows a cross-sectional view of creating an opening according toanother embodiment of the disclosure.

FIG. 5 shows a cross-sectional view of optionally increasing thecontrast of the layers in the opening according to one embodiment of thedisclosure.

FIG. 6 shows a cross-sectional view of creating an image of the layersin the opening according to one embodiment of the disclosure.

FIG. 7 shows an illustrative image of the layers in an opening accordingto one embodiment of the disclosure.

FIG. 8 shows a schematic view of layers of the opening for calculatinglayer thicknesses according to an embodiment of the disclosure.

FIG. 9 shows a cross-sectional view of layers of a repaired multilayercomponent according to an embodiment of the disclosure.

FIG. 10 shows a cross-sectional view of layers of a repaired multilayercomponent according to another embodiment of the disclosure.

It is noted that the drawings of the disclosure are not to scale. Thedrawings are intended to depict only typical aspects of the disclosure,and therefore should not be considered as limiting the scope of thedisclosure. In the drawings, like numbering represents like elementsbetween the drawings.

DETAILED DESCRIPTION OF THE INVENTION

As an initial matter, in order to clearly describe the currentdisclosure it will become necessary to select certain terminology whenreferring to and describing relevant parts of a multilayer component.When doing this, if possible, common industry terminology will be usedand employed in a manner consistent with its accepted meaning. Unlessotherwise stated, such terminology should be given a broadinterpretation consistent with the context of the present applicationand the scope of the appended claims. Those of ordinary skill in the artwill appreciate that often a particular component may be referred tousing several different or overlapping terms. What may be describedherein as being a single part may include and be referenced in anothercontext as consisting of multiple components. Alternatively, what may bedescribed herein as including multiple components may be referred toelsewhere as a single part.

Where an element or layer is referred to as being “on,” “engaged to,”“disengaged from,” “connected to” or “coupled to” another element orlayer, it may be directly on, engaged, connected or coupled to the otherelement or layer, or intervening elements or layers may be present. Incontrast, when an element is referred to as being “directly on,”“directly engaged to,” “directly connected to” or “directly coupled to”another element or layer, there may be no intervening elements or layerspresent. Other words used to describe the relationship between elementsshould be interpreted in a like fashion (e.g., “between” versus“directly between,” “adjacent” versus “directly adjacent,” etc.). Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

Embodiments of the disclosure provide a method to analyze quantitativedata, like layer thickness, of a multilayer component. The methodobtains the required quantitative data with a mini-invasive impact of amultilayer component. In particular, an opening is created in themultilayer component that can be fully restored, where necessary, usingavailable (local) repair procedures while enabling the reuse of thecommercial multilayer component. In addition, the component assessmentcan be performed during component manufacture and at the site of use.The component can be repaired on-site using on-site repair solutions.

FIG. 1 shows a perspective view of an illustrative multilayer component100 in the form of a turbine blade. The teachings of the disclosure canbe applied to any multilayer component made using any method offormation of the layers, e.g., welding, brazing, thermal spray, etc. Asshown in the cross-sectional view of FIG. 2, multilayer component 100may include a plurality of material layers. In the example shown, one ormore protective layers 106 may be over substrate 104. Substrate 104 mayinclude any metal or metal alloy that acts as a metal substrate, or aceramic such as ceramic matrix composite. For purposes of a turbineblade, substrate 104 may include, for example, a superalloy, which mayrefer to an alloy having numerous excellent physical characteristicscompared to conventional alloys, such as but not limited to: highmechanical strength, high thermal creep deformation resistance, etc.Superalloys include but are not limited to: Rene 108, CM247, Haynesalloys, Incalloy, MP98T, TMS alloys, CMSX single crystal alloys, N5, GTD444, MarM 247 and IN 738. Alternatively, substrate 104 can include avariety of other metals or metal alloys. “Gamma prime” (γ′) is theprimary strengthening phase in nickel-based alloys. Example high gammaprime superalloys include but are not limited to: Rene 108, N5, GTD 444,MarM 247 and IN 738. In one embodiment, bond coat 110 may include agamma-gamma prime structure (e.g., γ′ phase [Ni3(Al, Ti)] phase in gammamatrix γ-Ni(Co,Cr)), and in another embodiment, substrate 104 mayinclude a gamma-beta structure, e.g., β-NiAl phase in gamma matrixγ-Ni(Co,Cr). In terms of ceramic, substrate 104 can include any nowknown or later developed ceramic configured to perform in the hot gaspath environment.

Protective layer(s) 106 may include any now known or later developedprotective layer for, for example, protecting substrate 104 from a hot,corrosive environment. In one embodiment, protective layer(s) 106 mayinclude at least one of a bond coat 110 (also known as an overlay coatif used alone), and a top coat 112 over the bond coat (note, “top coat”does not necessarily indicate layer 112 as the outermost coating). Bondcoat 110 may include any now known or later developed bond coat materialsuch as but not limited to: nickel or platinum aluminides, nickelchromium aluminum yttrium (NiCrAlY) or nickel cobalt chromium aluminumyttrium (NiCoCrAlY). Bond coat 110 may include a gamma-gamma primestructure (e.g., γ′ phase [Ni3(Al, Ti)] phase in gamma matrixγ-Ni(Co,Cr)). In one embodiment, bond coat 110 may include a metal (M)with chromium-aluminum-yttrium alloy (MCrAlY) such as those commerciallyavailable from Amdry as model numbers 4522A, and 4522C. Bond coat 110may be applied using, for example, a high velocity oxygen fuel (HVOF)application, a low pressure plasma spraying (LPPS) or an atmosphericplasma spraying (APS).

A thermal barrier coating (TBC) layer 114 may be provided over bond coat110. TBC layer 114 material may include, for example, yttria-stabilizedzirconia (YSZ), mullite and alumina.

During operation, as shown in FIG. 3, elements may diffuse from bondcoat 110, creating a depletion layer 118, some of which may eventuallyoxidize, creating a thermally grown oxide layer 116 (hereinafter “oxidelayer 116”). Depending on substrate 104 composition and how bond coat110 is formed, oxide layer 116 may or may not be formed during operationby diffusion of aluminum, e.g., γ′ phase [Ni3(Al, Ti)] phase in gammamatrix γ-Ni(Co,Cr) from bond coat 110.

Three example arrangements of substrate 104 and bond coat 110 for whichembodiments of the disclosure are advantageous include the following. A)Substrate 104 with a MCrAlY bond coat 110 of gamma-gamma prime structureapplied by HVOF or LPPS, which exhibits depletion in bond coat 110,creating depletion layer 118, that is identifiable using the teachingsof the disclosure. Here, for example, aluminum diffuses and oxidized toform oxide layer 116. Embodiments of the disclosure allow formeasurement of the depletion of bond coat 110. B) Substrate 104 with aMCrAlY bond coat 110 of gamma-beta structure applied by APS. Here, asshown in FIG. 4, no depletion occurs and only bond coat 110 thickness ismeasured using embodiments of the disclosure, i.e., because degradationof bond coat 110 cannot be measured with this method. C) Substrate 104with a MCrAlY bond coat 110 of gamma-beta structure applied by HVOF orLPPS. This latter arrangement exhibits depletion layer 118 in bond coat110, as shown in FIG. 3, due to operation (like arrangement A) that isidentifiable using the teachings of the disclosure, i.e., aluminumdiffuses and oxidizes to form oxide layer 116. While two to threeprotective layers 106 have been illustrated, it is emphasized that theteachings of the disclosure are applicable to any number of layers andvarious diffusing element(s). Materials other than TBC can also beemployed.

FIGS. 3 and 4 also show creating an opening 120, i.e., a test siteopening, having a predefined geometry partially into multilayercomponent 100 at a selected location on a surface of the multilayercomponent 100. Prior to forming opening 120, in most cases as shown inFIG. 3, at least a portion of TBC layer 114 is removed, e.g., by grit orsand blasting. Only an area of TBC layer 114 necessary to create opening120, e.g., by drilling, needs to be removed. That is, not all of TBClayer 114 needs to be removed, only an area slightly larger than an areaof a tool used to make opening 120. Opening 120 can be created in anumber of ways to form a predefined geometry in multilayer component100. In one embodiment, shown in FIG. 3, opening 120 is created bydrilling to create a cone-shaped hole 122. Other holes of varying shapeare also possible. For example, FIG. 4 shows an opening 120 created bycalotte grinding to create a spherical segment opening 124. Othermaterial removal tools, e.g., a milling tool, can also be used to createa predefined geometry in multilayer component 100. “Predefined geometry”may include any shape for which the points, lines, surfaces, angles,lengths and other dimensions are known. As will be described, thepredefined geometry allows dimensions obtained from an image of opening120 to be used to calculate quantitative data about layers and inparticular bond coat 110, such as but not limited to: layer thicknesses,a depletion level, an inter-diffusion level, or the existence of a heataffected zone. In one example of the FIG. 3 embodiment, a drill bit mayhave a precise point angle between approximately 130 and 150°, and adiameter of, for example, approximately 2.5 millimeters to 7millimeters. A location of opening 120 can be user selected to, forexample, provide visual assessment of the components (new-make/afteruse) and define material properties, where desired. More than oneopening 120 can be used to test various localized areas of multilayercomponent 100. Dependent on component condition, different parameterscan be assessed at different locations without the conventionallimitations based on a specified cut-up plan for the component thatwould be required if destructive testing was used. Masks (not shown) canbe used for regular checks at reproducible locations.

As shown in FIG. 5 for the FIG. 3 drilling embodiment, opening 120exposes each of material layers 104, 110 (116, 118 where present)including substrate 104. That is, at least some portion of each layer104, 110 (116, 118 where present) is revealed by opening 120, e.g., asurface, a corner, an edge, etc. An opening 120 size may be based on avariety of factors such as but not limited to: coating thickness,expected worst case wall penetration thickness, minimum and/or maximumthickness of opening 120 desired, etc. An appropriate drill bit diameterand angle may be selected based on any of those factor(s). Substrate 104should be exposed to a minimal degree, and should be so exposed in amanner to not create a crack or other extensive damage therein. Drillingspeed and down pressure are precisely controlled to achieve the abovesituation.

In some cases, it is beneficial to increase the contrast compared tothat present after opening 120 is created. FIG. 5 also shows optionallyincreasing a contrast of the exposed plurality of material layers 104,110, 118 exclusively in opening 120. In one embodiment, the process caninclude polishing the exposed plurality of material layers 104, 106.This process may include, for example, polishing using a felt 140 with adiamond paste 142. In this case, increasing the contrast may alsooptionally include etching 144 the exposed plurality of material layers104, 106, e.g., after polishing. The etching may include using any nowknown or later developed etchant such as but not limited to: amolybdic-etchant for aluminum rich phases, or Murakami-etchant forchromium rich phases. The surface contrast can also be enhanced byelectrochemical etching. Polishing may be advantageous, for example,where bond coat 110 is depleted, such as in arrangements A) and C),described herein. In this fashion, embodiments of the disclosure canattain bond coat 110 thickness and depletion layer 118 thickness, i.e.,how much of bond coat 110 is diffused forming a depletion layer 118 (andoxide layer 116) and how much remains as bond coat 110. The depletionlayer 118 thickness and the bond coat 110 thickness can be related toremaining lifetime of bond coat 110, i.e., life expectancy of bond coat110. In other embodiments, it is not necessary to increase the contrast,i.e., there is no polishing or etching performed. This latter processmay be applied to certain bond coats 110 that are not depleted, e.g.,any deterioration is due to inner oxidation such as with arrangement B),described herein.

FIG. 6 shows creating an image of exposed plurality of material layers104, 106 in opening 120 using a digital microscope 150, e.g., a handheldand portable version. Digital microscope 150 may include any now knownor later developed microscope. In one embodiment, digital microscope 150can be handheld and portable so it can be used in the field of use ofmultilayer component, e.g., inside a turbine.

FIG. 7 shows an example image 152 of opening 120 and the exposedmaterial layers for a used multilayer component 100. It is understoodthat a newly manufactured multilayer component 100 would only have bondcoat 110 and substrate 104 present. A depth or thickness of bond coat110 can be calculated from image 152 based on the predefined geometry ofopening 120. FIG. 8 shows a schematic of dimensions pulled from image152 for opening 120 in FIG. 6, e.g., lateral diameters of layers d1, d2and d3 of layers 104, 110, 118, respectively. The predefined geometry ofopening 120 provides a known angle α of exposed surfaces of layers 104,110, 118. Application of trigonometry leads to T1=((d₂/2)-(d₁/2))tan β,and T2=((d₃/2)−(d₂/2))tan β. Angle β is the angle of opening 120relative to horizontal. Thus, the thickness of bond coat 110 (T1) can bedetermined. Further, where present, a thickness of depletion layer 118(T2) can be determined. The thickness of depletion layer 118 (T2)indicates an amount of depletion of bond coat 110. That is, thickness ofdepletion layer 118 can be used to determine the remaining life (lifeexpectancy) of bond coat 110.

Based on the calculated thickness(es), determinations of quantitativedata can be ascertained such as but not limited to: bond coat 110thickness, i.e., intact bond coat 110 thickness, and depletion layer 118thickness resulting from the diffusion process. For new manufacture, athickness of bond coat 110 can be used to confirm, for example, thequality of the product and to benchmark bond coat thickness for laterevaluation. For used multilayer components 100, the amount of depletionof bond coat 110 can be used, for example, to project remaining lifeexpectancy using conventional algorithmic or empirically based modelingtechniques. For example, for a known bond coat material, if 50% of bondcoat 110 is used, it may indicate it has 1200 operating hours left underexpected operating conditions of multilayer component 100. Further, thethickness of bond coat 110 and/or the thickness of depletion layer 118can also be used to determine life expectancy of bond coat 110.

In contrast to conventional destructive material testing, multilayercomponent 100 can be assessed, and can be repaired, where necessary.That is, opening 120 can be repaired, allowing multilayer component 100to be used for an intended purpose thereof, e.g., as an airfoil. Therepairing process can include any now known or later developed repairprocesses for an opening 120 in the materials provided. For example,substrate 104 and bond coat 110 repair may include at least one of laserwire welding or tungsten inert gas (TIG) welding. The repairing devicemay be handheld. Alternatively, substrate 104 and/or bond coat 110 maybe repaired by a thermal spray process, e.g., APS, flame spraying, etc.TBC layer 114 repair may include any thermal spray process such as oneof APS and flame spraying. Alternatively, TBC 114 may include a slurrycoating process. Oxide layer 116 is not repaired. FIG. 9 shows opening120 (for FIG. 3 embodiment) repaired.

As noted, embodiments of the method described herein may be performedprior to use of the multilayer component 100, i.e., after manufacture,to confirm proper fabrication and/or benchmark layer thicknesses.Alternatively, embodiments of the disclosure can be performed at ageographic location of use of multilayer component 100, e.g., a powerplant in the case of a turbine rotor blade. Where multilayer component100 is on site, it can be dismounted from its use setting, or it canremain in its use setting, e.g., inside a turbine. If it remains inplace, multilayer component 100 can be used after the repairing ofopening 120, e.g., without reinstallation. If on site, the repairing ofopening 120 may include using at least one handheld device, e.g., TIGwelder, flame spray, etc.

FIG. 9 shows a cross-sectional view of a used (i.e., ex-service)multilayer component 100 after exposure to methods according toembodiments of the disclosure. Multilayer component 100 may include asubstrate 104, a bond coat 110 over substrate 104, and a TBC layer 114over bond coat 110. TBC layer 114 has a first outer surface 170 havingindications of exposure to a hot gas path environment, e.g., from use ina gas turbine. That is, first outer surface 170 may be, for example,dirty, worn, and/or have a different color or shade. A filled opening172 is in substrate 104, bond coat 110 and, where provided, TBC layer114. Oxide layer 116 and/or depletion layer 118 may exist outside offilled opening 172. Filled opening 172 includes a substrate repair fill164, including material that is either identical to or similar to(perhaps better properties) the metal of substrate 104, that fillsfilled opening 172 in substrate 104, i.e., in a substrate portion 160 ofopening 120. Multilayer component 100 also includes a bond coat repairfill 174 filling filled opening 172 in bond coat 110, i.e., in a bondcoat portion 168 of opening 120. Bond coat repair fill 174 includesmaterial either identical or similar to (perhaps better properties) bondcoat 110. As shown, since opening 120 in substrate 104 is very small,substrate repair fill 164 may be the same material as bond coat repairfill 174, i.e., repair fill 164 and 174 are the same. In this situation,bond coat repair fill 174 extends into substrate 104. A thermal barriercoating (TBC) plug 176 fills filled opening 172 in TBC layer 114, i.e.,where TBC layer 114 was removed. TBC plug 176 has a second outer surface176 having no or less indications of exposure than first outer surface170 of TBC layer 114 since it has not seen an operation atmosphere andtemperature or has been applied with a different manufacturing process,i.e., it is newer (maybe with slightly different properties e.g.porosity) and has less dirt thereon, and may have a differentcolor/shading than TBC layer 114. Either of TBC plug 176 (shown) or bondcoat repair fill 174 may fill filled opening 172 in oxide layer 116and/or depletion layer 118. In the FIG. 9 example, opening 120 has aperiphery having at least a portion with a cone-shape. It is understoodthat where opening 120 according to the FIG. 4 embodiment is employed,opening 120 would have a periphery having at least a spherical shapedportion. In any event, however, as shown in FIG. 9, the periphery ofopening 120 is invisible to the naked eye in an outermost layer, e.g.,TBC layer 114 and TBC plug 176. A final repair process may includecontouring outer surfaces 170, 176 of multilayer component 100, e.g., bygrinding or polishing.

FIG. 10 shows another embodiment in which the repair includes onlyrepairing substrate 104 with substrate repair fill 164, and bond coat110 with bond coat repair fill 174, in filled opening 172. Here,depletion layer 118, oxide layer 116 and TBC layer 114 are not present.Again, since opening 120 in substrate 104 is very small, substraterepair fill 164 may be the same material as bond coat repair fill 174,i.e., repair fill 164 and 174 are the same. TBC layer 114 is notprovided or repaired. A final repair process may include contouring asurface 154 of multilayer component 100, e.g., by grinding or polishing.In FIG. 10, opening 120 existence is invisible to the naked eye onsurface 154. However, if cut open, remnants of opening 120 may beobserved in multilayer component 100.

Embodiments of the disclosure provide quantitative assessment (e.g.,thickness, depletion, bonding, heat affected zone, etc.) of a multilayercomponent (e.g., substrate with coating, brazing, welding, etc.) havinga minimal destructive impact on the commercial component while enablingits reuse by a localized material restoration, where necessary. Themethod thus avoids full metallurgical investigation bysectioning/destruction of commercial parts, and avoids scrap-parts formetallurgical investigation of multilayer components. In addition, themethods allow for condition-based repair, and enables repair scopereduction compared to destructive testing techniques. The methods can beused during manufacture or after use, in the field.

The foregoing drawings show some of the processing associated accordingto several embodiments of this disclosure. In this regard, it shouldalso be noted that in some alternative implementations, the acts notedmay occur out of the order described or, for example, may in fact beexecuted substantially concurrently or in the reverse order, dependingupon the act involved. Also, one of ordinary skill in the art willrecognize that additional steps that describe the processing may beadded.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. “Optional” or “optionally” means thatthe subsequently described event or circumstance may or may not occur,and that the description includes instances where the event occurs andinstances where it does not.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” “approximately” and “substantially,” are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged, such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.“Approximately” as applied to a particular value of a range applies toboth values, and unless otherwise dependent on the precision of theinstrument measuring the value, may indicate +/−10% of the statedvalue(s).

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A method of analyzing layer thickness of amultilayer component, the method comprising: creating an opening havinga predefined geometry partially into the multilayer component at aselected location on a surface of the multilayer component, wherein themultilayer component includes a plurality of material layers including asubstrate and a bond coat and the opening exposes each of the pluralityof material layers including the substrate; creating an image of theexposed plurality of material layers in the opening using a digitalmicroscope; and calculating at least a thickness of the bond coat of theexposed plurality of material layers from the image and based on thepredefined geometry of the opening.
 2. The method of claim 1, whereinthe bond coat includes MrCrAlY, and the plurality of material layersfurther includes a depletion layer over the bond coat, and furthercomprising determining a thickness of the depletion layer.
 3. The methodof claim 2, further comprising determining a life expectancy of the bondcoat based on the at least one of the thickness of the depletion layerand the thickness of the bond coat.
 4. The method of claim 2, whereinthe plurality of material layers further includes an oxide layer overthe depletion layer.
 5. The method of claim 1, wherein the openingcreating includes drilling to create a cone-shaped hole.
 6. The methodof claim 1, further comprising increasing a contrast of the exposedplurality of material layers exclusively in the opening from thatpresent after the opening creating.
 7. The method of claim 6, whereinthe increasing contrast includes: polishing the exposed plurality ofmaterial layers; and etching the exposed plurality of material layers.8. The method of claim 7, wherein the polishing includes using a feltwith a diamond paste, and the etching includes using an etchant.
 9. Themethod of claim 1, wherein the plurality of material layers includes anoxide layer over the bond coat and the bond coat over the substrate. 10.The method of claim 1, further comprising repairing the opening,allowing the multilayer component to be used for an intended purposethereof.
 11. The method of claim 1, wherein prior to the drilling, themultilayer component further includes a thermal barrier coating (TBC)layer over the oxide layer, and further comprising removing at least aportion of the TBC layer prior to the drilling, and wherein therepairing includes repairing the at least a portion of the TBC layer.12. The method of claim 1, wherein the method is performed prior to useof the multilayer component.
 13. The method of claim 12, wherein priorto the drilling, the multilayer component further includes a thermalbarrier coating (TBC) layer over the bond coat, and further comprisingremoving at least a portion of the TBC layer prior to the drilling, andwherein the repairing includes repairing the at least a portion of theTBC layer.
 14. The method of claim 1, wherein the method is performed ata geographic location of a use site of the multilayer component.
 15. Themethod of claim 14, wherein the repairing the opening includes using atleast one handheld device.
 16. A multilayer component, comprising: asubstrate; a bond coat over the substrate; a thermal barrier coating(TBC) layer over the bond coat, the TBC layer having a first outersurface indications of exposure to a hot gas path environment; and afilled opening in the substrate, the bond coat and the TBC layer, thefilled opening including: a substrate repair fill filling the filledopening in the substrate, a bond coat repair fill filling the filledopening in the bond coat, and a thermal barrier coating (TBC) plugfilling the filled opening in the TBC layer, the TBC plug having asecond outer surface having no or less indications of exposure to thehot gas path environment than the first outer surface.
 17. Themultilayer component of claim 16, wherein the substrate repair fillfilling the filled opening in the substrate is the same material as thebond coat repair fill filling the filled opening in the bond coat.
 18. Amethod of analyzing layer thickness of a multilayer component, themethod comprising: drilling to create an opening having a predefinedgeometry partially into the multilayer component at a selected locationon a surface of the multilayer component, wherein the multilayercomponent includes a plurality of material layers including a substrate,a bond coat over the substrate, and wherein the opening exposes each ofthe plurality of material layers; increasing a contrast of the exposedplurality of material layers exclusively in the opening from thatpresent after the opening creating by polishing the exposed plurality ofmaterial layers, and etching the exposed plurality of material layers;creating an image of the exposed plurality of material layers in theopening using a digital microscope; calculating a thickness of the bondcoat from the image and based on the predefined geometry of the opening;and repairing the opening, allowing the multilayer component to be usedfor an intended purpose thereof.
 19. The method of claim 18, wherein themethod is performed at a geographic location of a field of use site ofthe multilayer component.
 20. The method of claim 18, wherein prior tothe drilling, the multilayer component further includes a thermalbarrier coating (TBC) layer over the oxide layer, and further comprisingremoving the TBC layer prior to the drilling, and wherein the repairingincludes repairing the TBC layer.